The following relates to the optical device arts, optical lens arts, zoom lens arts, and related arts.
Adjustable zoom lenses find diverse applications, such as in machine vision inspection systems, computer vision systems used as input devices by computers, gaming consoles, mobile devices (cell phones, tablet computers, laptop computers), and other interactive electronic devices, and so forth. In a typical system, a monochromatic imaging device including a lens and a digital imaging array (e.g. CCD array, CMOS imaging array, or so forth) is provided along with an illuminator outputting at an infrared wavelength or other wavelength of interest for real-time image capture and processing. Monochromatic illumination is useful to avoid chromatic aberration or other chromatic distortion effects, but polychromatic illumination may also be used to obtain beneficial spectral information. In one approach, the imaging system employs a fixed-lens camera that captures the entire frame within the camera's field of view, and subsequent image processing is employed to isolate and identify a feature of interest of an object under inspection, or to isolate and recognize a user input action.
In such a system, the field of view must be large enough to ensure the object feature, user action of interest, or the like is captured in the image. However, providing a sufficiently large field of view may limit the spatial resolution. To avoid this limitation, an optical zoom can be provided. In this variant, the zoom is adjusted to provide a wide field of view. Image processing is applied to the wide-field image to identify a feature of interest, which is then zoomed in and imaged at higher resolution.
However, mechanical zoom lens systems are typically bulky, and the zoom speed is limited by the mechanical response time of the zoom system. This can be problematic for systems that need to be made small, such as a user interface camera designed to fit into the bezel of a portable computer or mobile device, or in systems or devices needing high speed zoom adjustment.